Integrated process for the production of 1-chloro-3,3,3-trifluoropropene

ABSTRACT

The present invention is directed to processes for the production of 1233zd from 240fa and HF, with or without a catalyst, at a commercial scale. The 240fa and HF are fed to a reactor operating at high pressure. The resulting product stream comprising 1233zd, HCl, HF, and other byproducts is treated to one or more purification techniques including phase separation and one or more distillations to provide purified 1233zd, which meets commercial product specifications, i.e., having a GC purity of 99.5% or greater.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims domestic priority to commonly owned, U.S.Provisional Patent Application Ser. No. 61/487,735, filed May 19, 2011,the disclosure of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention related to the production of1-chloro-3,3,3-trifluoropropene (1233zd) on a commercial scale from thereaction of 1,1,1,3,3-pentachloropropane (240fa) and HF. The compound1233zd is a low global warming compound that has applications as areplacement for high global warming materials, for example in foamblowing and aerosol propellant applications.

The designation 1233 is used herein to refer to all trifluoro,monochloro propenes, namely olefin compounds having the general formulaC₃H₂ClF₃. The designation 1233zd is used herein generically to refer to1,1,1-trifluo-3,chloro-propene, independent of whether it is the cisform or the trans form. The terms “cis-1233zd” and “trans-1233zd” areused herein to describe the cis- and trans-forms of1,1,1-trifluo-3-chlororopropene, respectively. The designation “1233zd”therefore includes within its scope cis-1233zd, trans-1233zd, and allcombinations and mixtures of these.

U.S. Pat. No. 6,844,475 teaches a process for producing 1233zd from240fa at low pressure and at temperatures lower than 150° C. Thedisclosure of this patent is hereby incorporated herein by reference.

U.S. Pat. No. 6,362,383 teaches a process for preparing1,1,1,3,3-pentafluoropropane (245fa) by (1) a first reaction step inwhich 1,1,1,3,3-pentachloropropane (240fa) is reacted with hydrogenfluoride in the liquid phase in the presence of a firsthydrofluorination catalyst under conditions that are suitable forobtaining a mixture of reaction products comprising1-chloro-3,3,3-trifluoropropene (1233zd) in substantial amount, and (2)a second reaction step in which the 1-chloro-3,3,3-trifluoropropene(1233zd) obtained from the first step is reacted with hydrogen fluoridein the liquid phase in the presence of a second hydrofluorinationcatalyst, and preferably while hydrogen chloride is continuously fed in,in order to obtain 1,1,1,3,3-pentafluoropropane (245fa). The disclosureof this patent is hereby incorporated herein by reference.

SUMMARY OF THE INVENTION

The present invention is directed to processes for the production of1233zd from 240fa and HF, with or without a catalyst, at a commercialscale. The 240fa and HF are fed to a reactor operating at high pressure.The resulting product stream comprising 1233zd, HCl, HF, and otherbyproducts is treated to a series of purification techniques includingphase separation and one or more distillations to provide purified1233zd, which meets commercial product specifications.

In one embodiment of the process, 240fa and HF are fed to a reactoroperating at high pressure (i.e., from 150 psig to 600 psig);

(a) the resulting product stream comprising 1233zd, HCl, HF, and otherbyproducts are distilled and the bottoms product, rich in HF, isrecycled to the reactor;

(b) the overhead product from the distillation column is fed to a seconddistillation column to remove the HCl;

(c) the HCl in the overhead stream is scrubbed with water and recoveredas an aqueous solution;

(d) the bottom stream from the second distillation column is then phaseseparated to recover HF;

(e) the HF rich top layer of the phase separation is recycled back tothe reactor; and

(f) the phase separation bottom layer components including the desired1233zd are scrubbed, dried and distilled to meet commercial productspecifications.

In another embodiment of the process, 240fa and HF are fed to a reactoroperating at high pressure. The resulting product stream comprising1233zd, HCl, HF, and other byproducts is partially condensed to recoverHF by phase separation. The recovered HF phase is recycled to thereactor. The HCl is scrubbed from the vapor stream and recovered as anaqueous solution. The remaining organic components including the desired1233zd are scrubbed, dried and distilled to meet commercial productspecifications.

The main difference between these two embodiments is that it has beendiscovered that the HF and organic do not easily phase separate if theHCl is still present, which is an unexpected result. Accordingly, in thepreferred embodiment, the HCl is removed first.

It should be appreciated by those persons having ordinary skill in theart(s) to which the present invention relates that any of the featuresdescribed herein in respect of any particular aspect and/or embodimentof the present invention can be combined with one or more of any of theother features of any other aspects and/or embodiments of the presentinvention described herein, with modifications as appropriate to ensurecompatibility of the combinations. Such combinations are considered tobe part of the present invention contemplated by this disclosure.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention as claimed. Other embodimentswill be apparent to those skilled in the art from consideration of thespecification and practice of the invention disclosed herein.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment of the process, 240fa and HF are fed to a reactoroperating at high pressure. The resulting product stream comprising1233zd, HCl, HF, and other byproducts are distilled and the bottomsproduct, rich in HF, is recycled to the reactor. The overhead productfrom the distillation column is fed to another distillation column toremove HCl. The HCl in the overhead stream is scrubbed with water andrecovered as an aqueous solution. The bottom stream from distillationcolumn is phase separated to recover HF. The HF rich top layer of thephase separation is recycled back to the reactor. The phase separationbottom layer components including the desired 1233zd are scrubbed, driedand distilled to meet commercial product specifications.

As described above, one embodiment of the present invention provides aprocess for the production of 1233zd from 240fa and HF, with or withouta catalyst, at a commercial scale. The details of this process are asfollows:

-   -   (1) High pressure liquid phase reaction of 240 and HF, with or        without a catalyst, forming 1233zd, its byproducts, HCl and        unreacted HF;    -   (2) First distillation of the stream from step (1) and recycle        of the bottoms to the reactor of step (1);    -   (3) Second distillation of the overhead stream of step (2);    -   (4) Separation and recovery of the HCl rich overhead stream of        step (3) as an aqueous solution in water;    -   (5) Phase separation of the bottoms stream of step (3) to form        an HF rich layer and an organic rich layer, with recycle of the        HF rich layer to the reactor of step (1);    -   (6) The organic rich layer from step (5) is fed to a caustic        scrubber to remove any remaining acidity and dried with an        appropriate drying agent such as sulfuric acid or molecular        sieves; and    -   (7) The acid-free, dry stream from step (6) is distilled to        produce 1233zd meeting all product specifications.

If desired, the process steps may be modified such that HF is removed instep (5), for example, by using absorption in sulfuric acid.

As described above, the high pressure liquid phase reaction of 240 andHF, with or without a catalyst, yields a product stream comprising1233zd, byproducts, HCl and unreacted HF. In certain embodiments thepressure range is from 150 psig to 600 psig. In certain embodiments, amore preferred pressure range is from 230 psig to 500 psig and a mostpreferred pressure range is from 350 psig to 450 psig.

In certain embodiments, the catalyst choices are selected from knownLewis acid catalysts. The preferred catalysts are TiCl₄ or SbCl₅, withTiCl₄ being more preferred. In certain embodiments, the most preferredchoice is operation of the reactor without employing any catalyst.

The typical byproducts observed in the reaction stream are precursors to1233zd such as 241fa, 242fa, and 243fa. These can easily be separatedfrom the reaction stream using known techniques and recycled.

The HCl recovery step entails the feeding of the organic layer from thesecond distillation to an HCl recovery system to remove and recover HClas a solution in water. In certain embodiments, the HCl is recoveredusing a packed-bed scrubber and falling-film absorber to form ahigh-strength solution that may be sold or used as a raw material forother processes, such as the production of calcium chloride. Optionally,the HCl may be distilled in a simple distillation column using alow-temperature cooling medium (−40° C. to −100° C.) to obtain a streamthat is essentially-free of HF, which may be more desirable as acommercially saleable product.

In certain embodiments, the phase separation takes place in a vesselappropriate to allow for separation of the organic and HF phases such asa simple horizontal tank. The phase separation takes place at a similartemperature and pressure as the condensation of the previous step. Asdescribed above, this step can also include the recycle of the HF-richlayer back to the reactor in step (1). In certain embodiments, theHF-layer is collected in a vessel and fed continuously back to thereactor of step (1).

As described above, in this step the HCl-free organic components aredistilled to remove recyclable intermediates to 1233zd. In certainembodiments the materials distilled are higher-boiling precursors to1233zd such as 241fa and 242fa. These materials may be present in rangesof 1% to 20% of the crude 1233zd stream.

In step (6), the overhead stream from step (5) is fed to a causticscrubber to remove any remaining acidity and dried with an appropriatedrying agent such as sulfuric acid or molecular sieves. In certainembodiments, the drying agents that are appropriate may be selected fromknown materials such as: 3A to 5A molecular sieves, high strengthsulfuric acid, calcium sulfate and silica gels. In certain embodiments,the caustic scrubber consists of a packed-tower with a circulatingsolution of NaOH or KOH.

In step (7) the acid-free, dry stream from Step (6) is distilled toproduce 1233zd, meeting all commercial product specifications. Incertain embodiments, commercial product specifications include a GCpurity of 99.5% or greater, with low levels, e.g., less than 100 ppm, ofunsaturated compounds.

As used herein, the singular forms “a”, “an” and “the” include pluralunless the context clearly dictates otherwise. Moreover, when an amount,concentration, or other value or parameter is given as either a range,preferred range, or a list of upper preferable values and lowerpreferable values, this is to be understood as specifically disclosingall ranges formed from any pair of any upper range limit or preferredvalue and any lower range limit or preferred value, regardless ofwhether ranges are separately disclosed. Where a range of numericalvalues is recited herein, unless otherwise stated, the range is intendedto include the endpoints thereof, and all integers and fractions withinthe range. It is not intended that the scope of the invention be limitedto the specific values recited when defining a range.

It should be understood that the foregoing description is onlyillustrative of the present invention. Various alternatives andmodifications can be devised by those skilled in the art withoutdeparting from the invention. Accordingly, the present invention isintended to embrace all such alternatives, modifications and variancesthat fall within the scope of the appended claims.

What is claimed is:
 1. A process for the manufacture of 1233zdcomprising the steps of: (a) reacting 240fa and HF in the liquid phaseand in the absence of a catalyst in a reactor operating at high pressureto produce a product stream comprising 1233zd, HCl, HF, and otherbyproducts; (b) distilling the product stream from step (a) into a firstoverhead product and a first bottoms product rich in HF; (c) distillingthe first overhead product from step (b) to form a second overheadproduct containing HCl and a second bottoms product containing organiccomponents and HF; (d) phase separating the second bottoms product fromstep (c) to separate the HF from the organic components; and (e) causticscrubbing, drying, and distilling the organic components from step (d)to provide purified 1233zd; wherein the reactor pressure range is from150 psig to 600 psig; and wherein the compound 1233zd, produced in step(e) has a purity of 99.5% or greater, as measured using gaschromatography.
 2. The process of claim 1, wherein the reactor pressurerange is from 230 psig to 500 psig.
 3. The process of claim 1, whereinthe reactor pressure range is from 350 psig to 450 psig.
 4. The processof claim 1, wherein the HF from step (b) is recycled to the reactor. 5.The process of claim 1, wherein the HCl from step (c) is scrubbed withwater and optionally recovered as an aqueous solution.
 6. The process ofclaim 1, wherein the HF from the phase separation in step (d) isrecycled back to the reactor.
 7. The process of claim 1, wherein thecaustic scrubbing is conducted with NaOH or KOH.
 8. The process of claim1, wherein the drying agent in step (e) comprises sulfuric acid.
 9. Theprocess of claim 1, wherein the drying agent in step (e) comprisesmolecular sieves.
 10. A process for making highly purified HCFC-1233zdby the reaction of 240fa and HF at a reactor pressure of from 150 psigto 600 psig wherein the purification of the HCFC-1233zd comprises thesteps of: (a) distilling the resulting product stream comprisingHCFC-1233zd, HCl, HF, and other byproducts; (b) distilling the overheadproduct from the step (a) distillation in a second distillation columnto remove the HCl; (c) phase separating the bottom stream from thesecond distillation in step (b) to isolate the HF; and (d) purifying thephase separation bottom layer components from step (c) to yield purifiedHCFC-1233zd having a purity of 99.5% or greater, as measured using gaschromatography.